One torsion damping device of the above kind is disclosed in particular in European published patent application No. EP 0 073 286A. In that disclosure, the peripheral resilient means act in a dry state. Having regard to their radial displacements under the effects of centrifugal force on the one hand, and to their relative displacements with respect to the rings (commonly known as guide rings) between which they are arranged, on the other hand, it is desirable to provide a degree of lubrication, at least in certain applications.
French published patent application No. FR 2 627 566A proposes, with the above in mind, to arrange the peripheral resilient means within a sealed annular housing, which is formed in two parts and fixed with respect to the support wheel. This housing then contains a lubricating fluid. It is arranged to carry and enclose within it a torsion damper comprising the peripheral resilient means, the damper plate and both guide rings. The two parts of the housing are fixed to each other radially outside the said resilient means, using appropriate fastening means. In addition, the torsion damper is fixed to one of the two parts of the sealed housing, while spacing rings connect the two parts together in a sealed manner in such a way as to allow the last-mentioned fastening means (for fastening the housing to the support wheel) to pass through.
However, in the corresponding practical embodiment, the sealed housing extends radially only within the circumference defining the pitch circle on which the fastening means securing the support wheel to the first shaft are arranged. In consequence, it is necessary first of all to fasten the support wheel on to the driving shaft before it is possible to fit the housing by means of its said spacer rings. Although this arrangement is satisfactory in service, the assembly operation is somewhat complicated.
In addition, in line with the securing means for the support wheel, the thickness of the sealed housing is extended in the axial direction to that of the heads of the threaded fasteners, such as screws or bolts, which cooperate with the fastening means formed in the support wheel to secure the latter to the first shaft, to the detriment of the overall axial length of the assembly. Besides this, the presence of the spacers complicates the manufacture of the housing.